Ralf W Bauer

University Hospital Frankfurt, Frankfurt, Hesse, Germany

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Publications (133)254.47 Total impact

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    ABSTRACT: Rationale and objectives: This investigation aimed to evaluate the impact on treatment regimen and clinical outcome of dual-energy computed tomography (DECT) in patients with suspected gouty arthritis. Materials and methods: We retrospectively analyzed electronic medical records (EMR) of 39 patients (36 male, 3 female; age range, 36-85 years) who underwent DECT of peripheral joints because of suspected gouty arthritis. We assessed the prior medical history, lab results, treatment regimen, and medications before and after DECT, and changes in subjective severity of symptoms as stated by patients in the EMR. The presence of monosodium urate (MSU) crystals in the index joint was verified with DECT. Results: Several patients had a prior diagnosis of gout (n = 9), hyperuricemia (n = 6), rheumatoid arthritis (n = 3), or psoriatic arthritis (n = 3). Elevated uric acid blood levels were detected in 32 patients (82%) before DECT. On DECT, MSU crystals were detected in 23 patients (59%). Of the 36 cases, the current treatment regimen was modified after DECT to gout-specific therapy in 22 cases and other rheumatic diseases were targeted in 14 cases. Several medications were prescribed more frequently based after DECT compared to before DECT imaging, including steroids (n = 20 vs. n = 12, respectively), colchicine (n = 13 vs. n = 4, respectively), and urate-lowering medication (n = 18 vs. n = 11, respectively). A subjective reduction of clinical symptoms during cumulative follow-up was reported by 34 patients (87.2%). Conclusions: Both positive and negative findings of MSU crystals on DECT have a significant impact on the treatment regimen and clinical outcome of patients with suspected gouty arthritis and facilitate differentiation from other rheumatic diseases.
    No preview · Article · Dec 2015 · Academic Radiology
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    ABSTRACT: To assess the effect of a noise-optimized image-based virtual monoenergetic imaging (VMI+) algorithm in direct comparison with the traditional VMI technique and standard linearly-blended images emulating 120-kVp acquisition (M_0.3) on image quality at dual-energy CT in patients with lung cancer.
    No preview · Article · Dec 2015
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    ABSTRACT: Purpose: To evaluate image quality and radiation dose in third-generation dual-source computed tomography (DSCT) of the neck using automated tube voltage adaptation (TVA) with advanced modelled iterative reconstruction (ADMIRE) algorithm. Methods: One hundred and sixteen patients were retrospectively evaluated. Group A (n = 59) was examined on second-generation DSCT with automated TVA and filtered back projection. Group B (n = 57) was examined on a third-generation DSCT with automated TVA and ADMIRE. Age, body diameter, attenuation of several anatomic structures, noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), radiation dose (CTDIvol) and size-specific dose estimates (SSDE) were assessed. Diagnostic acceptability was rated by three readers. Results: Age (p = 0.87) and body diameter (p = 0.075) did not differ significantly. Tube voltage in Group A was set automatically to 100 kV for all patients (n = 59), and to 70 kV (n = 2), 80 kV (n = 5), and 90 kV (n = 50) in Group B. Noise was reduced and CNR was increased significantly (p < 0.001). Diagnostic acceptability was rated high in both groups, with better ratings in Group B (p < 0.001). SSDE was reduced by 34 % in Group B (20.38 ± 1.63 mGy vs. 13.04 ± 1.50 mGy, p < 0.001). Conclusion: Combination of automated TVA and ADMIRE in neck CT using third-generation DSCT results in a substantial radiation dose reduction with low noise and increased CNR. Key points: • Third-generation DSCT provides automated tube voltage adaptation with an increment of 10 kV. • 10 kV increment optimizes scans to the patient's neck anatomy. • TVA combined with ADMIRE significantly lower radiation dose in contrast-enhanced neck CT. • TVA in combination with ADMIRE reduces noise and increases SNR and CNR. • Image analysis quoted less noise and better diagnostic acceptability in third-generation DSCT.
    No preview · Article · Nov 2015 · European Radiology
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    ABSTRACT: Objective: The aim of the study was to evaluate objective and subjective image qualities of virtual monoenergetic imaging (VMI) in dual-source dual-energy computed tomography (DECT) and optimal kiloelectron-volt (keV) levels for lung cancer. Methods: Fifty-nine lung cancer patients underwent chest DECT. Images were reconstructed as VMI series at energy levels of 40, 60, 80, and 100 keV and standard linear blending (M_0.3) for comparison. Objective and subjective image qualities were assessed. Results: Lesion contrast peaked in 40-keV VMI reconstructions (2.5 ± 2.9) and 60 keV (1.9 ± 3.0), which was superior to M_0.3 (0.5 ± 2.7) for both comparisons (P < 0.001). Compared with M_0.3, subjective ratings were highest for 60-keV VMI series regarding general image quality (4.48 vs 4.52; P = 0.74) and increased for lesion demarcation (4.07 vs 4.84; P < 0.001), superior to all other VMI series (P < 0.001). Image sharpness was similar between both series. Image noise was rated superior in the 80-keV and M_0.3 series, followed by 60 keV. Conclusions: Virtual monoenergetic imaging reconstructions at 60-keV provided the best combination of subjective and objective image qualities in DECT of lung cancer.
    No preview · Article · Oct 2015 · Journal of computer assisted tomography
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    ABSTRACT: Background and purpose: Dose-saving techniques in neck CT cause increased image noise that can be counteracted by iterative reconstruction. Our aim was to evaluate the image quality of advanced modeled iterative reconstruction (ADMIRE) in contrast-enhanced low-tube-voltage neck CT. Materials and methods: Sixty-one patients underwent 90-kV(peak) neck CT by using third-generation 192-section dual-source CT. Image series were reconstructed with standard filtered back-projection and ADMIRE strength levels 1, 3, and 5. Attenuation and noise of the sternocleidomastoid muscle, internal jugular vein, submandibular gland, tongue, subscapularis muscle, and cervical fat were measured. Signal-to-noise and contrast-to-noise ratios were calculated. Two radiologists assessed image noise, image contrast, delineation of smaller structures, and overall diagnostic acceptability. Interobserver agreement was calculated. Results: Image noise was significantly reduced by using ADMIRE compared with filtered back-projection with the lowest noise observed in ADMIRE 5 (filtered back-projection, 9.4 ± 2.4 Hounsfield units [HU]; ADMIRE 1, 8.3 ± 2.8 HU; ADMIRE 3, 6.7 ± 2.0 HU; ADMIRE 5, 5.4 ± 1.7 HU; all, P < .001). Sternocleidomastoid SNR and internal jugular vein-sternocleidomastoid contrast-to-noise ratios were significantly higher for ADMIRE with the best results in ADMIRE 5 (all, P < .001). Subjective image quality and image contrast of ADMIRE 3 and 5 were consistently rated better than those for filtered back-projection and ADMIRE 1 (all, P < .001). Image noise was rated highest for ADMIRE 5 (all, P < .005). Delineation of smaller structures was voted higher in all ADMIRE strength levels compared with filtered back-projection (P < .001). Global interobserver agreement was good (0.75). Conclusions: Contrast-enhanced 90-kVp neck CT is feasible, and ADMIRE 5 shows superior objective image quality compared with filtered back-projection. ADMIRE 3 and 5 show the best subjective image quality.
    No preview · Article · Oct 2015 · American Journal of Neuroradiology
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    ABSTRACT: To compare quantitative image quality parameters in abdominal dual-energy computed tomography angiography (DE-CTA) using an advanced image-based (Mono+) reconstruction algorithm for virtual monoenergetic imaging and standard DE-CTA. Fifty-five patients (36 men; mean age, 64.2 ± 12.7 years) who underwent abdominal DE-CTA were retrospectively included. Mono + images were reconstructed at 40, 50, 60, 70, 80, 90 and 100 keV levels and as standard linearly blended M_0.6 images (60 % 100 kV, 40 % 140 kV). The contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) of the common hepatic (CHA), splenic (SA), superior mesenteric (SMA) and left renal arteries (LRA) were objectively measured. Mono+ DE-CTA series showed a statistically superior CNR for 40, 50, 60, 70 and 80 keV (P < 0.031) compared to M_0.6 images for all investigated arteries except SMA at 80 keV (P = 0.08). CNR at 40 keV revealed a mean relative increase of 287.7 % compared to linearly blended images among all assessed arteries (P < 0.001). SNR of Mono+ images was consistently significantly higher at 40, 50, 60 and 70 keV compared to M_0.6 for CHA and SA (P < 0.009). Compared to linearly blended images, Mono+ reconstructions at low keV levels of abdominal DE-CTA datasets significantly improve quantitative image quality. • Mono+ combines increased attenuation with reduced image noise compared to standard DE-CTA. • Mono+ shows superior contrast-to-noise ratios at low keV compared to linearly-blended images. • Contrast-to-noise ratio in monoenergetic DE-CTA peaks at 40 keV. • Mono+ reconstructions significantly improve quantitative image quality at low keV levels.
    No preview · Article · Sep 2015 · European Radiology
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    ABSTRACT: To evaluate a novel monoenergetic reconstruction algorithm (nMERA) with improved noise reduction for dual-energy CT (DECT) of pancreatic adenocarcinoma. Sixty patients with suspected pancreatic carcinoma underwent dual-source dual-energy CT with arterial phase. Images were reconstructed as linearly-blended 120-kV series (M_0.6) and with the standard monoenergetic (sMERA) and the novel monoenergetic algorithm (nMERA) with photon energies of 40, 55, 70 and 80keV. Objective image quality was compared regarding image noise, pancreas attenuation, signal-to-noise ratio (SNR) and pancreas-to-lesion contrast. Subjective image quality was assessed by two observers. Thirty pancreatic adenocarcinomas were detected. nMERA showed significantly reduced image noise at low keV levels compared with sMERA images (55 keV: 7.19±2.75 vs. 20.68±7.01HU; 40 keV: 7.33±3.20 vs. 37.22±14.66HU) and M_0.6 (10.69±3.57HU). nMERA pancreatic SNR was significantly superior to standard monoenergetic at 40 (47.02±23.41 vs. 9.37±5.83) and 55 keV (28.29±16.86 vs. 9.88±7.01), and M_0.6 series (11.42±6.00). Pancreas-to-lesion contrast peaked in the nMERA 40 keV series (26.39±16.83) and was significantly higher than in all other series (p<0.001). nMERA 55 keV images series were consistently preferred by both observers over all other series (p<0.01). nMERA DECT can significantly improve image quality and pancreas-to-lesion contrast in the diagnosis of pancreatic adenocarcinoma. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
    No preview · Article · Jul 2015 · European journal of radiology
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    ABSTRACT: To evaluate neck computed tomography (CT) with a reduced tube voltage of 80 kVp in patients with suspected peritonsillar abscess (PTA) regarding objective and subjective image quality, and the potential for dose reduction. Forty-seven patients with clinically suspected PTA were retrospectively analysed. Patients were examined using dual-source CT in dual-energy mode. The objective and subjective image quality of 80 kVp images were compared with linearly blended 120 kVp images (M_0.3; 30% of 80 kV, 70% of 140 kV spectrum). Attenuation of abscess rim enhancement, central necrosis, and several other anatomical landmarks were measured. The signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and rim-to-abscess CNR (raCNR) were calculated. Radiation dose was assessed as size-specific dose estimates (SSDE). Subjective image quality was assessed according to the European guidelines on quality criteria for CT. Interobserver agreement was calculated using the intraclass correlation coefficient (ICC). Attenuation of inflamed soft tissue (141.7 ± 16.3 versus 93.7 ± 9.3 HU, p < 0.001), CNR (9.6 ± 4.8 versus 5.6 ± 3.8, p = 0.001), raCNR (14.3 ± 5.9 versus 12.4 ± 4.4, p = 0.02), and subjective image sharpness (3.6 ± 0.6 versus 2.8 ± 0.7, p < 0.001) were significantly increased in the 80 kVp compared to 120 kVp, whereas subjective and objective image noise were significantly increased with 80 kVp acquisition (p < 0.001). Overall interobserver agreement was almost perfect (ICC, 0.87). Calculated SSDE of 80 kVp acquisition was decreased by 49.7% compared to 120 kVp (10.58 ± 0.76 versus 21.04 ± 1.43 mGy, p < 0.001). Low-tube-voltage 80 kVp neck CT provides increased enhancement of soft-tissue inflammation, CNR, raCNR, and improved abscess delineation in patients with PTA compared to standard 120 kVp acquisition while resulting in a significant reduction of radiation exposure. Copyright © 2015 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
    No preview · Article · Jun 2015 · Clinical Radiology
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    ABSTRACT: To investigate the association between aortic root calcification (ARC) and coronary artery calcification (CAC) assessed by coronary artery calcium-scoring dual-source computed tomography (DSCT). We retrospectively analyzed 143 consecutive patients who underwent coronary artery calcium-scoring during coronary DSCT angiography. 57 patients had findings of ARC on calcium-scoring scans. ARC volume (ARCV) and Agatston coronary artery calcium score (CACS) were calculated. Chi-square test was used to assess differences of categorical variables between patients with and without ARC. Statistical significances between both groups were assessed with the independent-Sample t test. Compared with patients without ARC (n=86), patients with ARC (n=57) showed a significantly higher presence of CAC (87.7% vs. 24.4%; P<0.001), and a higher mean CACS (700.6±941.2 vs. 256.4±724.3; P=0.009) in patients with CAC. Patients with a calculated ARCV >40mm(3) (n=32) showed significantly higher rates of severe CAC (56.3% vs. 24.0%; P=0.014) compared with patients with an ARCV<40mm(3) (n=25). Compared with patients without CAC (n=42), patients with CAC (n=101) showed a significantly higher presence of ARC (83.3% vs. 50.5%; P<0.001) and a higher mean ARCV (95.4±116.2mm(3) vs. 29.7±33.0 mm(3); P=0.003). Severe CAC (n=24) correlated with an increased mean ARCV (122.3±148.8mm(3)) compared to patients with minimal to moderate CAC (n=33, mean ARCV: 61.9±64.8mm(3); P<0.05). The extent of ARC is directly associated with the presence and degree of CAC on calcium-scoring scans during coronary DSCT angiography. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
    No preview · Article · Jun 2015 · European Journal of Radiology
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    ABSTRACT: To compare radiation exposure and image quality of second-generation 128-slice dual-source CT (DSCT) coronary angiography (cCTA) protocols. We retrospectively analyzed data from four groups with 25 patients, each examined by one of the following DSCT cCTA protocols: prospectively ECG-gated high-pitch (group 1) or sequential (group 2) acquisition, retrospectively ECG-gated acquisition in dual-energy (DECT, group 3) or dual-source (group 4) mode. CT dose index volume, dose length product, estimated radiation dose, contrast-to-noise- and signal-to-noise-ratios were compared. Subjective image quality was rated by two observers blinded to the protocols. High-pitch DSCT showed a mean estimated radiation dose of 1.27 ± 0.62 mSv, significantly (p < 0.01) lower than sequential (2.04 ± 0.94 mSv), dual-energy (3.97 ± 1.29 mSv) or dual-source (8.11 ± 4.95 mSv) acquisition. Image noise showed no statistical difference (p > 0.91), ranging from 15.2 ± 4.4 (group 2) up to 24.5 ± 22.0 (group 4). Each protocol showed diagnostic image quality in at least 98.1 % of evaluated coronary segments without significant differences (p > 0.05). Prospectively ECG-gated DSCT protocols enable cCTA with significant dose reduction and consistently diagnostic image quality. In patients requiring retrospectively ECG-gated DSCT for functional analysis or due to arrhythmia, dual-energy mode should be preferred over dual-source mode as it significantly decreases estimated dose without compromising image quality.
    No preview · Article · May 2015 · La radiologia medica
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    ABSTRACT: To investigate and compare the use of automated tube potential selection (ATPS) with automated tube current modulation (ATCM) in high-pitch dual-source computed tomographic angiography (CTA) for imaging the whole aorta without electrocardiogram synchronization. Two groups of 60 patients underwent CTA on a dual-source computed tomographic device in high-pitch mode: ATCM (with 100-kV fixed tube potential) was used in group 1 and ATPS (with the same image quality options) in group 2. For the evaluation of radiation exposure, CT dose index and dose-length product were analyzed. Contrast and image quality were assessed by 2 independent observers. The ATPS group received a higher radiation dose than the ATCM group (P < 0.001) because in 80% of patients, the software switched to use of a 120-kV tube potential. In all cases, images of the aorta were of sufficient quality. High-pitch dual-source CTA of the aorta using ATPS is feasible in clinical routine, but is associated with higher radiation exposure than the ATCM protocol. This finding contradicts previously evaluations of ATPS based on single-source techniques.
    No preview · Article · May 2015 · Journal of computer assisted tomography

  • No preview · Article · Apr 2015 · RöFo - Fortschritte auf dem Gebiet der R
  • A Bucher · M Kerl · M Albrecht · J Wichmann · T Vogl · R Bauer

    No preview · Article · Apr 2015 · RöFo - Fortschritte auf dem Gebiet der R
  • S Fischer · N Schultheis · P Dewes · J Scholtz · M Kerl · T Vogl · R Bauer

    No preview · Article · Apr 2015 · RöFo - Fortschritte auf dem Gebiet der R

  • No preview · Article · Apr 2015 · RöFo - Fortschritte auf dem Gebiet der R

  • No preview · Article · Apr 2015 · RöFo - Fortschritte auf dem Gebiet der R

  • No preview · Article · Apr 2015 · RöFo - Fortschritte auf dem Gebiet der R
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    ABSTRACT: Background Inferior vein graft patency after coronary artery bypass grafting (CABG) is attributed to various factors. Venous valves may limit flow, cause thrombus formation, and diminish diastolic backflow. The aim of our study was to compare clinical outcome and midterm patency rate of valvulotomized vein grafts and arterial grafts in patients undergoing CABG. Methods Between 2007 and 2010, valvulotomized saphenous vein segments were used to graft the right coronary artery (RCA) in 147 patients undergoing CABG with mean 2.8 ± 1 arterial and 1.5 ± 0.6 venous anastomoses. Outcome, reintervention, and reoperation were assessed after 4 ± 1.6 years. Intraoperative bypass flow rate was measured before and after valvulotomy of venous bypass grafts in 12 patients. Patency of the grafts was assessed by means of multislice computed tomography (MSCT) in 45 patients. Results A total of 102 patients underwent isolated CABG and 45 had combined procedures. In-hospital mortality was 2%. At 4 years' clinical follow-up, 95% of the patients were asymptomatic. Five patients underwent recoronary angiography because of angina pectoris. The MSCT and reangiography patency rate of all valvulotomized saphenous vein grafts was 97.1 versus 95.8% of arterial grafts 18 ± 6 months postoperatively. Intraoperative measurements showed a significant increase (+20.2 mL/min; p = 0.01) of flow in the venous bypass grafts to the RCA after valvulotomy. There were no reoperations at the latest follow-up. Conclusion Patients with valvulotomized venous grafts had good clinical outcome. The one-year patency rate of those grafts is comparable to that of arterial grafts. However, long-term results and angiography studies will be needed to strengthen these findings. Georg Thieme Verlag KG Stuttgart · New York.
    No preview · Article · Apr 2015 · The Thoracic and Cardiovascular Surgeon
  • Ralf W. Bauer · Sebastian Fischer
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    ABSTRACT: Dual-energy CT (DECT) is a steadily emerging innovative imaging modality. Various applications have been developed and applied to successfully solve diagnostic difficulties that standard CT has in the abdomen. This includes kidney stone differentiation, cholesterol gallstone detection, renal and adrenal lesion characterization, and tumor response monitoring. This article is supposed to give a current update on possible applications of DECT in the abdomen and their evidence.
    No preview · Article · Apr 2015
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    ABSTRACT: To investigate low-tube-voltage 80-kVp computed tomography (CT) of head and neck primary and recurrent squamous cell carcinoma (SCC) regarding objective and subjective image quality. We retrospectively evaluated 65 patients (47 male, 18 female; mean age: 62.1 years) who underwent head and neck dual-energy CT (DECT) due to biopsy-proven primary (n = 50) or recurrent (n = 15) SCC. Eighty peak kilovoltage and standard blended 120-kVp images were compared. Attenuation and noise of malignancy and various soft tissue structures were measured. Tumor signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Subjective image quality was rated by three reviewers using 5-point grading scales regarding overall image quality, lesion delineation, image sharpness, and image noise. Radiation dose was assessed as CT dose index volume (CTDIvol). Interobserver agreement was calculated using intraclass correlation coefficient (ICC). Mean tumor attenuation (153.8 Hounsfield unit (HU) vs. 97.1 HU), SNR (10.7 vs. 8.3), CNR (8.1 vs. 4.8), and subjective tumor delineation (score, 4.46 vs. 4.13) were significantly increased (all P < 0.001) with 80-kVp acquisition compared to standard blended 120-kVp images. Noise of all measured structures was increased in 80-kVp acquisition (P < 0.001). Overall interobserver agreement was good (ICC, 0.86; 95 % confidence intervals: 0.82-0.89). CTDIvol was reduced by 48.7 % with 80-kVp acquisition compared to standard DECT (4.85 ± 0.51 vs. 9.94 ± 0.81 mGy cm, P < 0.001). Head and neck CT with low-tube-voltage 80-kVp acquisition provides increased tumor delineation, SNR, and CNR for CT imaging of primary and recurrent SCC compared to standard 120-kVp acquisition with an accompanying significant reduction of radiation exposure.
    No preview · Article · Mar 2015 · Neuroradiology

Publication Stats

769 Citations
254.47 Total Impact Points

Institutions

  • 2014-2015
    • University Hospital Frankfurt
      Frankfurt, Hesse, Germany
  • 2007-2015
    • Goethe-Universität Frankfurt am Main
      • Institut für Diagnostische und Interventionelle Radiologie
      Frankfurt, Hesse, Germany
  • 2010-2013
    • Hospital Frankfurt Hoechst
      Frankfurt, Hesse, Germany
  • 2009-2011
    • Medical University of South Carolina
      • Department of Radiology
      Charleston, South Carolina, United States